Organisms at high altitude

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Alpine chough in flight

Organisms can live at high altitude, either on land, or while flying. Decreased oxygen availability and decreased temperature make life at high altitude challenging. Despite these environmental conditions, many species have been successfully adapted at high altitudes. Animals have developed physiological adaptations to enhance oxygen uptake and delivery to tissues which can be used to sustain metabolism. The strategies used by animals to adapt to high altitude depend on their morphology and phylogeny.

Land organisms[edit]

Plants[edit]

There is a moss that grows at 6480 m (21260 ft) on Mount Everest.[1] It may be the highest altitude plant species.[1]

Invertebrates[edit]

Tardigrades occur over the entire world, including the high Himalayas.[2] Tardigrades are also able to survive temperatures of close to absolute zero (−273 °C (−459 °F)),[3] temperatures as high as 151 °C (304 °F), 1,000 times more radiation than other animals,[4] and almost a decade without water.[5] Since 2007, tardigrades have also returned alive from studies in which they have been exposed to the vacuum of outer space in low earth orbit.[6][7]

Fish[edit]

Naked carp in Lake Qinghai at 3,205 m (10,515 ft)

Fish at high altitudes have a lower metabolic rate, as has been shown in highland westslope cutthroat trout compared to introduced lowland rainbow trout in the Oldman River basin.[8] There is also a general trend of smaller body sizes and lower species richness at high altitudes observed in aquatic invertebrates, likely due to lower oxygen partial pressures.[9][10][11] These factors may decrease productivity in high altitude habitats, meaning there will be less energy available for consumption, growth, and activity, which provides an advantage to fish with lower metabolic demands.[8]

The naked carp from Lake Qinghai, like other members of the carp family, can use gill remodelling to increase oxygen uptake in hypoxia.[12] The response of naked carp to cold and low-oxygen conditions seem to be at least partly mediated by hypoxia-inducible factor 1 (HIF-1).[13] It is unclear whether this is a common characteristic in other high altitude dwelling fish or if gill remodelling and HIF-1 use for cold adaptation are limited to carp.

Mammals[edit]

The Himalayan pika lives at altitudes up to 4,200 m (13,800 ft)

Small mammals at high altitude face the challenges of maintaining body heat in cold temperatures, due to their large volume-to-surface area ratio. As oxygen is used as a source of metabolic heat production, the hypobaric hypoxia at high altitudes is problematic. To convert fats to energy in the form of ATP, more oxygen is required than to convert the same amount of carbohydrates. The reason they use fats is believed to be because they have it in large stores, but also means that they must eat more or they will begin to lose weight.

A number of rodents live at high altitude, including deer mice, guinea pigs, and rats. A number of mechanisms help them survive these harsh conditions, including altered genetics of the hemoglobin gene in guinea pigs and deer mice.[14][15] Deer mice use a high percentage of fats as metabolic fuel at high altitude to retain carbohydrates for small burst of energy.[16]

Other physiological changes that occur in rodents at high altitude include increased breathing rate[17] and altered morphology of the lungs and heart allowing more efficient gas exchange and delivery. Lungs of high altitude mice are larger, with more capillaries,[18] and hearts of mice and rats at high altitude have a heavier right ventricle,[19][20] which pumps blood to the lungs.

At high altitudes, some rodents even shift their thermal neutral zone so they may maintain normal basal metabolic rate at colder temperatures.[21]

Flying animals[edit]

Birds[edit]

The Rüppell's vulture can fly up to 11.2 km (7.0 mi) above sea level

Birds have been especially successful at living at high altitudes.[22] In general, birds have physiological features that are advantageous for high-altitude flight. The respiratory system of birds moves oxygen across the pulmonary surface during both inhalation and exhalation, making it more efficient than that of mammals.[23] In addition, the air circulates in one direction through the parabronchioles in the lungs. Parabronchioles are oriented perpendicular to the pulmonary arteries, forming a cross-current gas exchanger. This arrangement allows for more oxygen to be extracted compared to mammalian concurrent gas exchange; as oxygen diffuses down its concentration gradient and the air gradually becomes more deoxygenated, the pulmonary arteries are still able to extract oxygen.[24] Birds also have a high capacity for oxygen delivery to the tissues because they have larger hearts and cardiac stroke volume (mL / min) compared to mammals of similar body size.[25] Additionally, they have an increased vascularization in flight muscle due to increased branching of capillaries and small muscle fibres (which increases surface-area-to-volume ratio).[26] These two features facilitate oxygen diffusion from the blood to muscle, allowing flight to be sustained during environmental hypoxia. Bird's hearts and brains, which are very sensitive to arterial hypoxia, are more vascularized compared to mammals.[27] The bar-headed goose (Anser indicus) is an iconic high flyer that surmounts the Himalayas during migration,[28] and serves as a model system for derived physiological adaptations for high-altitude flight. Rüppell's vultures, bar-headed geese, whooper swans, alpine chough, and common cranes all have flown more than 8 km above sea level.

Invertebrates[edit]

Insects can fly and kite at very high altitude. In 2008, a colony of bumble bees was discovered on Mount Everest at more than 5,600 metres above sea level, the highest known altitude for an insect. In subsequent tests some of the bees were still able to fly in a flight chamber which recreated the thinner air of 9,000 metres.[29]

Ballooning is a term used for the mechanical kiting[30][31] that many spiders, especially small species,[32] as well as certain mites and some caterpillars use to disperse through the air. Some spiders have been detected in atmospheric data balloons collecting air samples at slightly less than 5 km (16000 ft) above sea level.[33] It is the most common way for spiders to invade isolated islands and mountaintops.[34][35]

Space flight[edit]

Main article: Animals in space

Before human spaceflight various animals were launched into space, including monkeys, dogs, and insects, so that scientists could investigate the biological effects of space travel. The United States launched flights containing primate cargo primarily between 1948-1961 with one flight in 1969 and one in 1985. France launched two monkey-carrying flights in 1967. The Soviet Union and Russia launched monkeys between 1983 and 1996.

During the 1950s and 1960s the Soviet space program used a number of dogs for sub-orbital and orbital space flights. Most survived and the few that died were lost mostly through technical failures.

Later, animals and other organisms were also flown to investigate various biological processes and the effects microgravity and spaceflight might have on them. Bioastronautics is an area of bioengineering research which spans the study and support of life in space. Certain functions of organisms are mediated by gravity, such as gravitropism in plant roots, while metabolic energy normally expended in overcoming the force of gravity remains available for other functions. This may take the form of accelerated growth.

In May 2011, tardigrades and other extremophiles were sent into orbit on a Space Shuttle.[36][37][38]

See also[edit]

References[edit]

  1. ^ a b "High Altitude Plants". Adventurers and Scientists for Conservation. 
  2. ^ C.Michael Hogan. 2010. Extremophile. eds. E.Monosson and C.Cleveland. Encyclopedia of Earth. National Council for Science and the Environment, washington DC
  3. ^ Becquerel P. (1950). "La suspension de la vie au dessous de 1/20 K absolu par demagnetization adiabatique de l'alun de fer dans le vide les plus eléve". C. R. Hebd. Séances Acad. Sci. Paris 231: 261–263. 
  4. ^ Radiation tolerance in the tardigrade Milnesium tardigradum
  5. ^ Crowe, John H.; Carpenter, John F.; Crowe, Lois M. (October 1998). "The role of vitrification in anhydrobiosis". Annual Review of Physiology 60. pp. 73–103. doi:10.1146/annurev.physiol.60.1.73. PMID 9558455. 
  6. ^ Staff Space.com (8 September 2008). "Creature Survives Naked in Space". Space.com. Retrieved 2011-12-22. 
  7. ^ Mustain, Andrea (22 December 2011). "Weird wildlife: The real land animals of Antarctica". MSNBC. Retrieved 2011-12-22. 
  8. ^ a b Rasmussen, Joseph B.; Robinson, Michael D.; Hontela, Alice; Heath, Daniel D. (8 July 2011). "Metabolic traits of westslope cutthroat trout, introduced rainbow trout and their hybrids in an ecotonal hybrid zone along an elevation gradient". Biological Journal of the Linnean Society 105: 56–72. doi:10.1111/j.1095-8312.2011.01768.x. 
  9. ^ Verberk, Wilco C.E.P.; Bilton, David T.; Calosi, Piero; Spicer, John I. (11 March 2011). "Oxygen supply in aquatic ectotherms: Partial pressure and solubility together explain biodiversity and size patterns". Ecology 92 (8): 1565–1572. doi:10.1890/10-2369.1. PMID 21905423. 
  10. ^ Peck, L.S.; Chapelle, G. (2003). "Reduced oxygen at high altitude limits maximum size". Proceedings of the Royal Society of London 270: 166–167. doi:10.1098/rsbl.2003.0054. 
  11. ^ Jacobsen, Dean (24 September 2007). "Low oxygen pressure as a driving factor for the altitudinal decline in taxon richness of stream macroinvertebrates". Oceologia 154 (4): 795–807. doi:10.1007/s00442-007-0877-x. PMID 17960424. 
  12. ^ Matey, Victoria; Richards, Jeffrey G.; Wang, Yuxiang; Wood, Chris M. et al. (30 January 2008). "The effect of hypoxia on gill morphology and ionoregulatory status in the Lake Qinghai scaleless carp, Gymnocypris przewalskii". The Journal of Experimental Biology 211 (Pt 7): 1063–1074. doi:10.1242/jeb.010181. PMID 18344480. 
  13. ^ Cao, Yi-Bin; Chen, Xue-Qun; Wang, Shen; Wang, Yu-Xiang; Du, Ji-Zeng (6 October 2008). "Evolution and regulation of the downstream gene of hypoxia-inducible factor-1a in naked carp (Gymnocypris przewalskii) from Lake Qinghai, China". Journal of Molecular Evolution 67 (5): 570–580. doi:10.1007/s00239-008-9175-4. PMID 18941827. 
  14. ^ Storz, J.F.; Runck, A. M.; Moriyama, H.; Weber, R. E.; Fago, A (1 August 2010). "Genetic differences in hemoglobin function between highland and lowland deer mice". The Journal of Experimental Biology 213 (15): 2565–2574. doi:10.1242/jeb.042598. PMC 2905302. PMID 20639417. 
  15. ^ Pariet, B.; Jaenicke, E. (24 August 2010). Zhang, Shuguang, ed. "Structure of the altitude adapted hemoglobin of guinea pig in the R-state". PloS One 8 (5): e12389. doi:10.1371/journal.pone.0012389. PMC 2927554. PMID 20811494. 
  16. ^ Cheviron, Z.A.; Bachman, G. C.; Connaty, A. D.; McClelland, G. B.; Storz, J. F (29 May 2010). "Regulatory changes contribute to the adaptive enhancement of thermogenic capacity in high-altitude deer mice". Proceedings of the National Academy of Sciences of the United States of America. 22 109 (22): 8635–8640. doi:10.1073/pnas.1120523109. PMC 3365185. PMID 22586089. 
  17. ^ Yilmaz, C.; Hogg, D.; Ravikumar, P.; Hsia, C (15 February 2005). "Ventilatory acclimatization in awake guinea pigs raised at high altitude". Respiratory Physiology and Neurobiology 145 (2–3): 235–243. doi:10.1016/j.resp.2004.07.011. PMID 15705538. 
  18. ^ Hsia, C.C.; Carbayo, J. J.; Yan, X.; Bellotto, D. J. (12 May 2005). "Enhanced alveolar growth and remodeling in guinea pigs raised at high altitude". Respiratory Physiology & Neurobiology 147 (1): 105–115. doi:10.1016/j.resp.2005.02.001. PMID 15848128. 
  19. ^ Preston, K.; Preston, P.; McLoughlin, P. (15 February 2003). "Chronic hypoxia causes angiogenesis in addition to remodelling in the adult rat pulmonary circulation". The Journal of Physiology 547 (Pt 1): 133–145. doi:10.1113/jphysiol.2002.030676. PMC 2342608. PMID 12562951. 
  20. ^ Calmettes, G.; Deschodt-Arsac, V.; Gouspillou, G.; Miraux, S. et al. (18 February 2010). Schwartz, Arnold, ed. "Improved energy supply regulation in chronic hypoxic mouse counteracts hypoxia-induced altered cardiac energetics". PloS One 5 (2): e9306. doi:10.1371/journal.pone.0009306. PMC 2823784. PMID 20174637. 
  21. ^ Broekman, M; Bennett, N.; Jackson, C.; Scantlebury, M. (30 December 2006). "Mole-rats from higher altitudes have greater thermoregulatory capabilities". Physiology and Behavior 89 (5): 750–754. doi:10.1016/j.physbeh.2006.08.023. PMID 17020776. 
  22. ^ McCracken, K. G.; Barger, CP; Bulgarella, M; Johnson, KP et al. (October 2009). "Parallel evolution in the major haemoglobin genes of eight species of Andean waterfowl". Molecular Evolution 18 (19): 3992–4005. doi:10.1111/j.1365-294X.2009.04352.x. PMID 19754505. 
  23. ^ "How the Respiratory System of Birds Works". Foster and Smith. Retrieved 21 December 2012. 
  24. ^ Moyes, C.; Schulte, P. (2007). Principles of Animal Physiology, 2/E. Benjamin-Cummings Publishing Company. ISBN 0321501551. 
  25. ^ Grubb, B.R. (October 1983). "Allometric relations of cardiovascular function in birds". American Journal of Physiology 245 (4): H567–72. PMID 6624925. 
  26. ^ Mathieu-Costello, O. (1990). Histology of flight: tissue and muscle gas exchange. In Hypoxia: The Adaptations. Toronto: B.C. Decker. pp. 13–19. 
  27. ^ Faraci, F.M. (1991). "Adaptations to hypoxia in birds: how to fly high". Annual Review of Physiology 53: 59–70. doi:10.1146/annurev.ph.53.030191.000423. PMID 2042973. 
  28. ^ Swan, L.W. (1970). "Goose of the Himalayas". Journal of Natural History 70: 68–75. 
  29. ^ Dillon, M. E.; Dudley, R. (2014). "Surpassing Mt. Everest: extreme flight performance of alpine bumblebees". Biology Letters 10 (2). doi:10.1098/rsbl.2013.0922. 
  30. ^ Flying Spiders over Texas! Coast to Coast. Chad B., Texas State University Undergrad: He correctly describes the mechanical kiting of spider "ballooning".
  31. ^ Artificial and Natural Flight By Hiram Stevens Maxim. Chapter on "Flying Kites", the "Balloon Spider" is correctly seen as mechanical kiting.
  32. ^ Valerio, C.E. (1977). "Population structure in the spider Achaearranea Tepidariorum (Aranae, Theridiidae)" (PDF). The Journal of Arachnology 3: 185–190. Retrieved 2009-07-18. 
  33. ^ VanDyk, J.K. (2002–2009). "Entomology 201 - Introduction to insects". Department of Entomology, Iowa State University. Retrieved 18 July 2009. 
  34. ^ Hormiga, G. (2002). "Orsonwells, a new genus of giant linyphild spiders (Araneae) from the Hawaiian Islands" (PDF). Invertebrate Systamatics 16 (3): 369–448. doi:10.1071/IT01026. Retrieved 2009-07-18. 
  35. ^ Bilsing, S.W. (May 1920). "Quantitative studies in the food of spiders" (PDF). The Ohio Journal of Science 20 (7): 215–260. Retrieved 2009-07-18. 
  36. ^ NASA Staff (2011-05-17). "BIOKon In Space (BIOKIS)". NASA. Retrieved 2011-05-24. 
  37. ^ Brennard, Emma (2011-05-17). "Tardigrades: Water bears in space". BBC. Retrieved 2011-05-24. 
  38. ^ "Tardigrades: Water bears in space". BBC Nature. 2011-05-17.